Thursday, August 1, 2013

Scab on Mandan

Scab lesions on Mandan pecans
     Mandan is one of the newer pecan cultivars developed by the USDA . Because it produces large, early ripening nuts, it has created considerable interest among northern pecan growers. When its was released, Mandan was promoted  having "good scab resistance".  This is the third year we have fruited Mandan but this summer has been the first time our Mandan trees have been exposed to conditions favorable for the spread of pecan scab.
   Once the rains kicked in this summer, I was able to find scab lesions on our Mandan nuts (photo above). Finding that Mandan is susceptible to scab does not surprise me.  I found scab lesions on Mandan twigs shortly after we grafted this cultivar into our orchard back in 2011. To me, Mandan seems to be similar to Pawnee in terms of susceptibility to pecan scab.
   Scab can be controlled on Mandan with a fungicide program but the kernel quality issues I've seen with this cultivar will prevent me from propagating additional trees.